Effect of cryo-storage on germinability and biochemical changes in papaya (Carica papaya L.) seeds

Abstract

The seeds of papaya, based on seed storage behaviour, are classified under “intermediate seed” category as they exhibit freezing injury even at low moisture content. Hence, the present study was initiated to investigate the germinability and biochemical changes of papaya seeds stored at vapour phase (-140℃) of liquid nitrogen for about six months. At monthly intervals, seed viability and biochemical parameters like total carbohydrate, total free sugars, total protein content and total free amino acids were assessed in the cryo-stored papaya seeds. The results showed that the germination percentage decreased from 90 % to 7 % in cryo-stored CO 2 variety of papaya as compared to fresh seeds. Similar response was also observed in TNAU Papaya CO 8 wherein the germination was reduced from 85 % to 23 % after cryo storage. The results also revealed that biochemical proximates, carbohydrate and protein content decreased after upon six months of cryo-storage in comparison to fresh seeds of both papaya genotypes. The level of free sugars and free amino acids increased gradually with the storage period. From the results of the present study, it is evident that seed viability loss could occur in papaya seeds upon long period of storage at extremely low temperature conditions which might possibly be accounted for the drastic reduction in biochemical components such as carbohydrates and proteins, key factors activately participating in seed physiology and biochemistry.

Keywords

• Papaya
• liquid nitrogen
• seed viability
• biochemical proximates
• cryo-conservation